211616921 has 4 divisors (see below), whose sum is σ = 211679412. Its totient is φ = 211554432.

The previous prime is 211616903. The next prime is 211616939. The reversal of 211616921 is 129616112.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (211616903) and next prime (211616939).

It can be written as a sum of positive squares in 2 ways, for example, as 46854025 + 164762896 = 6845^2 + 12836^2 .

It is a cyclic number.

It is not a de Polignac number, because 211616921 - 2¹⁰ = 211615897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (211616941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25856 + ... + 33041.

It is an arithmetic number, because the mean of its divisors is an integer number (52919853).

Almost surely, 2^211616921 is an apocalyptic number.

It is an amenable number.

211616921 is a deficient number, since it is larger than the sum of its proper divisors (62491).

211616921 is an equidigital number, since it uses as much as digits as its factorization.

211616921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62490.

The product of its digits is 1296, while the sum is 29.

The square root of 211616921 is about 14547.0588436288. The cubic root of 211616921 is about 595.9138286975.

It can be divided in two parts, 21161 and 6921, that added together give a palindrome (28082).

The spelling of 211616921 in words is "two hundred eleven million, six hundred sixteen thousand, nine hundred twenty-one".